This invention relates to a xerographic toner cartridge, and process for manufacturing the same.
In the practice of xerography, an electrostatic image of a desired pattern is formed on an insulating surface. This is usually accomplished by providing a photoconductive insulating material affixed to a conductive backing, uniformly electrostatically charging the photoconductive surface (typically by a corona charging technique), and subsequently exposing the charged photoconductive surface to an electromagnetic radiation pattern (usually a visible light pattern) of the image to be reproduced. The electromagnetic radiation pattern discharges the photoconductive surface in the areas where the surface is irradiated, thus forming an electrostatic charge pattern on the photoconductive surface corresponding to the pattern of the desired image.
In order to render the image defined by the electrostatic charge pattern visible and permanent, the photoconductive surface is contacted with microscopic particles which may be in the form of a fine powder, the particles having been provided by some means with an electrostatic charge opposite in sign to the charge remaining on those portions of the photoconductor which have not been discharged (or which have only been partially discharged) by the incident electromagnetic radiation. As a result, these microscopic particles, commonly known as "toner", adhere to the photoconductor only in those areas which retain an electrostatic charge, i.e. those areas which have not been irradiated.
The pattern of toner particles, which corresponds to the pattern of the desired image, is subsequently either (i) fused to the photoconductive surface by application of heat or a suitable solvent to form a permanent image, or (ii) transferred to another surface, which may comprise ordinary paper, and subsequently fused thereto by suitable application of heat or solvent.
The toner powder is normally contained within a toner dispenser situated adjacent a developer tank which contains a mechanism for delivering the toner particles to the photoconductor surface. The toner powder is discharged from the toner dispenser to the sump of the developer tank as copies are produced, resulting in gradual depletion of toner powder from the dispenser. As a result, it is necessary to periodically add toner powder to the toner dispenser to replenish the supply thereof.
This periodic addition of toner powder to the toner dispenser of the copier is normally performed by a machine operator dressed in street clothing. In many cases, the operator pours toner powder from a small plastic bottld into the dispenser. Since the toner powder is extremely fine and is pigmented with coloring matter such as carbon black, the toner powder tends to form a toner "cloud" while being poured and may cause the operator's hands and clothing to become dirty.
In an effort to enable the operator to replenish the toner supply without soiling of hands and clothing, and to provide a reservoir for additional toner (thus effectively increasing the toner storage capacity of the copying machine), a number of arrangements have been devised which employ toner cartridges that can be placed in the copier and opened after they are in position. Such cartridges commonly employ a slidable cardboard seal situated adjacent the open end of the cartridge. The cartridge is inserted into the copier in an inverted position atop the toner dispenser, i.e. with the seal-covered open end downward, and the seal is slid from the cartridge and the adjacent portion of the toner dispenser to permit the toner powder within the cartridge to fall into the dispenser.
Such friction sealed cartridges, however, do not provide a sufficiently tight seal to fully accomplish the desired objectives. As a result, some of the fine toner powder within the cartridge escapes when the cartridge is subjected to shock and vibration in shipment or handling, so that when the carton containing the cartridge is opened, the interior of the carton and part or all of the outer surface of the cartridge is covered with black toner powder; thus the cartridge and packing cannot be handled without soiling the operator's hands and clothing. In addition, a small quantity of toner may escape from the cartridge when the same is inverted and subjected to some pressure while being inserted into the copier; this escaping toner is likely to cause additional soiling.
Attempts to provide a tighter seal by, e.g., bonding paper to the cartridge opening with a weak cement, have resulted in additional problems, in that in many cases the paper seal tears while being removed from the cartridge while the cartridge is in the copier. As a result, it becomes impossible to remove the partially opened inverted cartridge from the copier without causing extensive spillage of toner within the machine and heavy soiling of the operator's hands and clothing.
Accordingly, an object of the present invention is to provide a reliable sealed toner cartridge which substantially eliminates any possibility of toner leakage during shipping and handling of the cartridge, and which has a sealing member which can be rapidly, reliably and easily removed when desired.
As herein described, there is provided a xerographic toner cartridge comprising a toner container having an elongated surface opening and a peripheral lip surrounding the opening. The opening is covered by an elongated flexible smooth-surfaced tongue having a length greater than twice the length of the opening. The tongue has longitudinal spaced sealing and tab portions, the length of the sealing portion being less than the length of the tab portion. The tonque is secured to the peripheral lip of the cartridge by an adhesive bond having a peel strength substantially less than the shear strength of the tongue. The tongue has a fold between its sealing and tab portions.
Also described herein is a process for manufacturing a xerographic toner cartridge, comprising the steps of providing a toner container having an elongated surface opening therein with a peripheral lip surrounding said opening, positioning an elongated flexible tongue adjacent said lip so that said tongue covers said opening, the length of said tongue being greater than twice the length of said opening, disposing a heat-activatable adhesive layer between said tongue and said lip, contacting said tongue with a heated platen to press said tongue against said lip for a time sufficiently long to activate said adhesive while at the same time providing insufficient heat transfer to deteriorate any toner situated within said container, and folding the free portion of said tongue to dispose said free portion adjacent the bonded portion thereof to form a tab, the free end of said tongue protruding beyond said lip.